Apparatus for use in detecting the passage of objects



y 1951 A. R. CARPENTER ET AL 2,

APPARATUS FOR USE IN DETECTING THE PASSAGE OF OBJECTS Filed Oct. 11-, 1948 2 Sheets-Sheet l @GQQ N @I@@ FIG. 3.

I N V EN T 0R5 HLFKD B MRD Gea /V762 wsgi'r oyuMna/Ebur y 1, 1951 A. R. CARPENTER ET AL 2,550,970

APPARATUS FOR USE IN DETECTING THE PASSAGE OF OBJECTS Filed Oct. 11, 1948 2 Sheets-Sheet 2 FIG-6 Patented May 1, 1951 UNITED STATES TENT OFFICE APPARATUS FOR USE IN DETECTING THE PASSAGE OF OBJECTS England Application October 11, 1948, Serial No. 53,778 In Great Britain October 29, 1947 22 Claims. 1 The present invention relates to apparatus of the type designed for use in detecting the passage of objects, in which the application of pressure to a part at least of the apparatus by the passing object results in a displacement of fluid within the apparatus, which displacement is adapted to perform a desired function in associated apparatus.

One use of such apparatus is in road trafiic signalling systems in which the apparatus is in the form of a pneumatic detector pad fitted in the roadway and in which the displacement of air within the detector pad, due to the pressure applied-by passing vehicles, is caused to operate associated apparatus controlling the operation of road traflic signals.

The object of the present invention is to provide improved apparatus of the type specified. According to the present invention apparatus of the type specified comprises in combination two or more base members adapted to be secured to a solid foundation and each provided with at least one straight groove or recess extending from side. to side of the member, said members being adapted to be arranged relative to one another so. that the longitudinal axes of the grooves or recesses are approximately colinear and said grooves or recesses form a substantially continuous channel through said base members, a flexible fluid container adapted to extend throughout the major part at least of said channel, and a resilient member adapted to fit within said container and be positioned so as to hold part of thebuter surface of said container in contact with. part at least of the base of said channel throughout the length thereof, the arrangement being such that an object passing over said apparatus would tend to deform at least that part of said container with which it makes contact, within the bounds of said channel, thereby causing a displacement of the fluid in said container.

The base members may be provided with two substantially parallel grooves or recesses which are arranged relative to one another so that the longitudinal axes of corresponding grooves or recesses in each base member are colinear, thereby forming two substantially parallel channels each of which is provided with one of said flexible fluid containers secured by one of said resilient members One embodiment of the present invention will now be described, by way of example, as applied to a pneumatic detector pad for use in trafiic signalling. The embodiment will be described with referroadence to the accompanying drawings in which:

Figure 1 shows a plan view of the assembled detector pad, whilst Figure 2 shows a side elevation thereof.

Figure 3 shows a resilient bar for fixing a tube in position, before insertion in the tube.

Figure 4 shows a partly sectional plan view of one end of the assembled detector pad, giving details of a termination box, whilst Figure 5 shows a sectional elevation taken along the line A-A in Figure 4.

Figure 6 is a sectional elevation taken along the line B-B in Figure 4 to show the arrangement of the tubes within a base member.

Referring more particularly to Figures 1 and 2 it will be seen that the detector pad is built up on a framework consisting of two parallel metal bars I supported between two termination boxes 2. Four base members 3 are supported by the bars l, which members 3 may, for example, be formed from a rectangular plate and are shaped so as to provide two parallel channels or grooves 4 (Figure 6), U-shaped, or almost square, in cross-section, which extend from side to side of the plate parallel to the shorter side thereof. The portions of the base member 3 on either side of the channels 4 are bent at an angle of approximately 45 degrees towards the outer vertical limb of the adjacent channel 4 to form wing portions 5. The fold between these wing portions 5 and their adjacent channel 4 is shaped so that the base member 3 can be fitted over the two metal bars I of the framework with the inside of the fold in contact with the metal bars I, and the channels 4 parallel thereto. During manufacture the wing portions 5 are tapered to reduce the length of the outer side of the wing portion 5 parallel to the channel 4, and a number of holes 6 are cut in each wing portion 5. An additional plate I is fixed Within the fold between the two channels 4, projecting at right angles to the plane of the base of the channels and extending in the same general direction as the wing portions 5. This additional plate 1 is also provided with a number of holes (not visible in drawings). The base members 3 are arranged with a small gap between adjacent members, and thus provide two substantially continuous parallel channels extending between the termination boxes 2.

Two flexible tubes 8, which may for example be of reinforced rubber, are laid in the channels d and are each secured in position by a curved resilient bar 9 (Figures 3 et seq.) which fits within the tube 8, extends throughout the length thereof and is clamped at each end by a connecting block l6 forming part of the termination box 2, the curved bar 9 being forcibly straightened, from the form shown in Figure 3, when clamped. Each resilient bar 9 is of corresponding cross-section to that of the channels s and is so dimensioned that it supports the sides of the flexible tube 8 and prevents the unsupported ceiling of the tube 8 from being pressed into contact with any other portion of the interior surface thereof. The top surface of each of the tubes 8 stands slightly above the level of the base members 3 (see Figure 6) so that the tubes 8 will be depressed by vehicles passing over the pad, the majority of the wheel weight being taken by the top surface ii of the base members 3- and the adjacent road surface.

The connecting blocks iii in each of the termination boxes 2 in addition to holding down the resilient bar 9 serve to make an air-tight and water-tight junction between each flexible tube BQand the pneumatic pipeline (not shown) which may connect the nipple l2 with associated pneumatic apparatus in the pavement or in other detector assemblies further across the road. The end of the tube 8 is a push fit on a spigot or nipple t3. formed in the connecting block 18 and is secured thereon by clips M. A suitable sealing compound may also be used to ensure air-tight connections.

Due to the small gap left between adjacent base members 3, the parallel bars I of the framework may be bent slightly so that the pad can be deformed tov follow the general camber of the road surface with which it is to be incorporated.

In usethe. detector pad is either incorporated inthe concrete road foundation or in a concrete emplacement. The wing portions and the central plate I of each base member 3 are embedded inthe concrete which fills the holes in the wing portions 5 and the central plate I. The angle which the wing portions 5 make with the horizontalcorresponds approximately to the direction ofthe thrustimposed on the outer edges of the two channels 6 by rolling wheels; thus apart from adhesion of the concrete to the surface of the wing portions 5 any relative movement between the wing portions 5 and the concrete is resisted by the'double shear strength of the concrete which fills the holes inthe wing portions 5 and, in the downward and outward direction, by the edges of the wing portions 5 against the solid concrete. Inorder to increase the resistance provided by the; edges. of the wing portions 5, the tapering sides may be-suitably shaped, for example they maybe stepped or serrated as shown in the drawings. The additional central plate I of the members 3 serves a similar purpose to that of the wing portions 5.

It will be appreciated that by virtue of the pressure applied by the resilient bars 5 each flexible tube 8 is held firmly in position so that it cannot readily be forced out of position, for example by skidding wheels. At the same time however it is a comparatively simple matter to remove a tube 8' when desired by slackening the nuts securing the connecting block it by which the resilient bar 9 is clamped, and removing the clips M- which secure the tubes 8 to the spigots or nipples E3 in the connecting blocks iii. Thus servicing or replacement of tubes 8 may be performed with a minimum of interference to traiiic.

Although in the embodiment described four base members were used it will be understood that the number used will depend upon the length of detector pad required, so that with the exception of the flexible tubes and resilient bars standard parts may be used for pads having a wide range of lengths between the termination boxes which approximately are multiples, greater than one, of the length of a base member. Moreover where the length of detector pad required does not correspond to an integral multiple of base members, one or more base members of length difierent from that of the standard base members may be used, for example a base member may be foreshortened as shown by the dotted line 16 in Figure 1.

It will be understood that the channels 4 in the base members 3 may take other cross-sectional forms, for example semi-circular, and the resilient bar 9 will then have to be given a cross-section to correspond. Moreover the groove or recess in a base member may be provided by two upstanding lips, so that the bottom of the groove or recess is in fact approximately level with the main horizontal surfaces of the member.

The invention may of course be applied to detector pads using only one flexible tube; the use of two tubes is, however, a known method used to prevent actuation of the associated equipment by a vehicle proceeding in the opposite direction to the normal traffic stream.

In the past the damping of air column oscillations in detector pads using air as thefluid medium has been achieved by means of baffles fitted in the connecting pipes. It has been found convenient, however, in detector pads according to the present invention to provide damping means within the flexible tubes themselves. Such damping means may, for example, take the form of loosely packed cotton waste or, alternatively, flock or kapok contained in tubes of open-weave canvas or webbing which are'slid into the flexible detector tubes.

We claim:

1. Apparatus for the detection of passing objects comprising in combination at. least two base members, each of said base members having at least one straight groove extending from side to side of the member, said members being constructed for securement to a solid foundation in such mutual relationship that. the longitudinal axes of the grooves are approximately colinear and said grooves form a substantially continuous channel through said base members, a flexible fluid container extending throughout the major part at least of said channel and having an opening at at least one of its extremities, and a resilient member fitted within said container and positioned so as to hold part of the outer surface of said container in contact with part at least of the base of said channel throughout the length thereof, whereby an object-passing over said apparatus would tend to deform at least that part of said container with which it makes contact, within the bounds of said channel, thereby causing a displacement of the. fluid in said container.

2. Apparatus according to claim 1 in which two substantially parallel grooves are provided in eachbase member, said base members being constructed for such mutual relationship that the longitudinal axes of corresponding grooves in each base member are colinear, thereby forming two substantially parallel channels each of which is provided with a flexible fluid container secured by a resilient member.

3. Apparatus according to claim 1 in which terminal members are provided for securement to the foundation at each end of a channel and position the ends of the resilient member.

4. Apparatus according to claim 3 in which the terminal member forms part of a termination box having means to which the fluid container and a fluid conduit are secured whereby displacements of fluid within said container may be communicated to apparatus adapted to be connected to said fluid conduit.

5. Apparatus according to claim 4 in which the termination box supports one end of at least one longitudinal bar, the other end of which is supported by a further box, said bar being positioned to support the base members.

6. Apparatus according to claim 5 in which a plurality of bars are provided and in which the base members are shaped so as to co-operate with the bars in such a manner that the longitudinal axes of the grooves in said members are approximately colinear.

7. Apparatus according to claim 1 in which terminal members are provided for securement to the foundation at each end of a channel and position the ends of the resilient member, the resilient member being bent from its unstressed shape by being so held, thereby securely retaining part of the outer surface of the container in contact with at least part of the base of said channel throughout the length thereof.

. 8. Apparatus according to claim 1 in which the cross-sectional shape of that part of the surface of the resilient member holding part of the outer surface of the container in contact with part at least of the base of the channel corresponds substantially to the cross-sectional shape of said part at least of the base of said channel.

9. Apparatus according to claim 1 in which the base members are each comprised by a plate having a central corrugated portion forming the groove, and wing portions on either side of said corrugated portion.

10. Apparatus according to claim 9 in which there are substantially flat portions of the plate bounding the groove, said flat portions being substantially level with the surface of the body in which the apparatus is to be incorporated.

11. Apparatus according to claim 10 in which the wing portions are provided with suitable apertures so that the material forming the solid foundation may be in intimate contact with the base members to prevent relative movement therebetween.

12-. Apparatus according to claim 1 in which the base members are each comprised by a plate having a central corrugated portion forming the groove, substantially flat portions which bound said groove and which may lie substantially level with the surface of the solid foundation in which the apparatus is to be incorporated, and wing portions on either side of said corrugated portion which each lie in a plane inclined to the plane containing said fiat portions so that said wing portions may extend into said solid foundation.

'13. Apparatus according to claim 12 in which the angle of inclination of the wing portions relative to the flat portions lies within the range of thirty to sixty degrees.

14. Apparatus according to claim 1 in which the base members are each comprised by a plate having two corrugated portions forming two of the grooves, substantially flat portions which bound each of said grooves and may lie substantially level with the surface of the solid foundation in which the apparatus is to be incorporated, and two wing portions one on each side of the corrugated portions which may project into the said solid foundation, and a central keel part which is secured to said plate between said two corrugated portions in a plane perpendicular to the plane containing said flat portions so that it may project into said solid foundation.

15. Apparatus according to claim 14 in which at least some of the edges of the wing portions and the keel part are serrated.

16. Apparatus according to claim 1 in which the base members are each comprised by a plate having a central corrugated portion forming the groove and substantially flat portions which bound said groove and may lie substantially level with the surface of the solid foundation in which the apparatus is to be incorporated, and the fluid container is constructed and arranged normally to project above the level of said flat portions, said fluid container being arranged to be deformed by an object traversing said apparatus so that at least that part of said container in contact with said object is depressed at least to the level of said flat portions.

17. Apparatus according to claim 1 in which the fluid container is provided with damping means within said container to damp fluid column oscillations within the fluid system of said container.

18. Apparatus according to claim 17 in which the damping means comprises a loosely packed mass of fibres.

19. Apparatus according to claim 18 in which the damping means includes open weave bags wherein the mass of fibres is contained.

20. Apparatus according to claim 1 in which the fluid within the container is air.

21. In a road trafiic signalling detector pad, at least two base members, said base members each being provided with at least one straight groove extending from side to side of the member and so located that the members may be arranged with the longitudinal axes of their respective grooves approximately colinear and thereby form a substantially continuous channel extending through said base members, a flexible fluid container, said container being constructed and arranged to extend throughout the major part at least of said channel, and a resilient member, said resilient member being constructed and arranged to fit within said container and positioned so as to hold part of the outer surface of said container in contact with part at least of the base of said channel throughout the length thereof.

22. In a road trafiic detecton'a base provided with at least one substantially continuous longitudinal channel, a flexible fluid container constructed and arranged to fit within said channel, and at least one resilient member constructed and arranged to fit within said container to secure said container to the base of said channel, said container being deformable by objects traversing said detector.

ALFRED RICHARD CARPENTER. HUBERT JOHIN NAPIER RIDDLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,037,583 Mapes Apr. 14, 1936 2,074,443 Walpole Mar. 23, 1937 

